This invention relates to a linking device for providing butting union for two plates which are placed in one plane with their respective edges butting on each other.
As is universally known, the upper cover for a corrugated cardboard box is formed by having the four vertical walls of said box bent at opposite upper edges of the box proper and extended in the form of flaps in mutually confronting directions. The upper opening of the box proper is closed by first bending one pair of opposed flaps into one common plane and then bending immediately thereon the other pair of opposed flaps into another common plane. Although the box can be kept closed by tying a cord around it, simple closure of the box is generally accomplished by fixing button-shaped catches one close to the edge of each of the confronting flaps and then connecting the two catches with a thin cord (such as a strong thread) passed around them so as to keep the folded pairs of flaps from being opened. Otherwise, there is adopted a method whereby a rubber strip each end of which is provided with a metal piece containing vertically raised claws is stretched across the line of abutment of the opposed flaps and, with the rubber strip kept in that stretched state, the claws are driven into said opposed flaps downwardly from their outer surface so as to keep the butting edges thereof from being opened.
Since these methods permit rather easy closure of the box, they have found widespread acceptance. Nevertheless, the devices used in these methods are very simple in construction and, therefore, have a disadvantage that they are easily disengaged and readily damaged and, after only a small number of uses, cease to function normally.
An object of the present invention is to provide a linking device capable of easy operation and providing safe butting union for two plates placed side by side.
Another object of the present invention is to provide a linking device capable of easy disengagement and permitting repeated use.